docs: def get_narrow_url(self, instance):
          """
          Return a link suitable for narrowing on the current item.
          """
          text = instance[0]
          request = self.context["request"]
          query_params = request.GET.copy()
  
          # Never keep the page query parameter in narrowing urls.
          # It will raise a NotFound exception when trying to paginate a narrowed queryset.
          page_query_param = self.get_paginate_by_param()
          if page_query_param and page_query_param in query_params:
              del query_params[page_query_param]
  
          selected_facets = set(query_params.pop(self.root.facet_query_params_text, []))
          selected_facets.add("%(field)s_exact:%(text)s" % {"field": self.parent_field, "text": text})
          query_params.setlist(self.root.facet_query_params_text, sorted(selected_facets))
  
          path = "%(path)s?%(query)s" % {"path": request.path_info, "query": query_params.urlencode()}
          url = request.build_absolute_uri(path)
          return serializers.Hyperlink(url, "narrow-url")